Today, various types of display devices are used for various applications. In a general display device, one pixel includes three sub pixels for displaying red, green and blue, which are three primary colors of light, and this realizes color display.
However, conventional display devices have a problem that the range of colors which can be reproduced (referred to as the “color reproduction range”) is narrow. FIG. 25 shows a color reproduction range of a conventional display device which provides display by use of the three primary colors. FIG. 25 is an xy chromaticity diagram of an XYZ colorimetric system. The triangle, the apexes of which are three points corresponding to the three primary colors of red, green and blue, represents the color reproduction range. In the figure, colors of various objects existing in the natural world which have been clarified by Pointer (see Non-patent Document 1) are plotted with “x”. As can be seen from FIG. 25, there are object colors which are not encompassed in the color reproduction range. The display device which provides display by use of the three primary colors cannot display a part of the object colors.
In order to enlarge the color reproduction range of display devices, techniques for increasing the number of primary colors used for display have been proposed.
For example, as shown in FIG. 26, Patent Document 1 discloses a liquid crystal display device 800 in which one pixel P includes six sub pixels R, G, B, Ye, C and M which respectively display red, green, blue, yellow, cyan and magenta. FIG. 27 shows the color reproduction range of the liquid crystal display device 800. As shown in FIG. 27, the color reproduction range represented by the hexagon, the apexes of which are six points corresponding to the six primary colors substantially encompasses the object colors. As can be seen, the color reproduction range can be enlarged by increasing the number of primary colors used for display.
Patent Document 1 also discloses a liquid crystal display device in which one picture element includes four pixels respectively for displaying red, green, blue and yellow, and a liquid crystal display device in which picture element includes five pixels respectively for displaying red, green, blue, yellow and cyan. By use of four or more primary colors, the reproduction range can be enlarged as compared with that of a conventional display device which provides display by use of the three primary colors. In this specification, a display device which provides display by use of four or more primary colors will be referred to as a “multiple primary color display device”, and a liquid crystal display device which provides display by use of four or more primary colors will be referred to as a “multiple primary color liquid crystal display device”.